From ab407e385fed5a896e75db9f99d9a4bec8f0daa5 Mon Sep 17 00:00:00 2001
From: Mads Kiilerich <mads@kiilerich.com>
Date: Mon, 24 Oct 2022 15:53:39 +0200
Subject: [PATCH] PoC: Implement += -= *= /= for control point editing

For example, if editing a control point at 7 dB and entering "+= 3"
in the input field instead of "7", it will set the control pointto 10
dB.

This is especially useful when editing multiple automation points at
once.
---
 gtk2_ardour/automation_line.cc      | 50 +++++++++++++++++++++++------
 gtk2_ardour/automation_line.h       |  2 +-
 gtk2_ardour/control_point_dialog.cc |  6 ++--
 gtk2_ardour/control_point_dialog.h  |  2 +-
 gtk2_ardour/editor_mouse.cc         |  2 +-
 5 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/gtk2_ardour/automation_line.cc b/gtk2_ardour/automation_line.cc
index 4aca2e43d88..9a9648947d2 100644
--- a/gtk2_ardour/automation_line.cc
+++ b/gtk2_ardour/automation_line.cc
@@ -390,26 +390,58 @@ AutomationLine::delta_to_string (double delta) const
  *  @return Corresponding y fraction.
  */
 double
-AutomationLine::string_to_fraction (string const & s) const
+AutomationLine::string_to_fraction (string const & s, double const old_fraction) const
 {
-	double v;
-	sscanf (s.c_str(), "%lf", &v);
-
+	bool is_db = false;
 	switch (_desc.type) {
 		case GainAutomation:
 		case BusSendLevel:
 		case EnvelopeAutomation:
 		case TrimAutomation:
 		case InsertReturnLevel:
-			if (s == "-inf") { /* translation */
-				v = 0;
-			} else {
-				v = dB_to_coefficient (v);
-			}
+			is_db = true;
 			break;
 		default:
 			break;
 	}
+	double v;
+	if ((s.length() > 2) && index("+-*/", s[0]) && (s[1] == '=')) {
+		v = old_fraction;
+		view_to_model_coord_y (v);
+		if (is_db) {
+			v = accurate_coefficient_to_dB(v);
+		}
+		double op_v;
+		sscanf (s.c_str() + 2, "%lf", &op_v);
+		if (op_v != 0.f) {
+			switch (s[0]) {
+				case '+':
+					v += op_v;
+					break;
+				case '-':
+					v -= op_v;
+					break;
+				case '*':
+					v *= op_v;
+					break;
+				case '/':
+					if (op_v > 1.0) {
+						v /= op_v;
+					}
+					break;
+			}
+		}
+	} else {
+		sscanf (s.c_str(), "%lf", &v);
+	}
+
+	if (is_db) {
+		if (s == "-inf") { /* translation */
+			v = 0;
+		} else {
+			v = dB_to_coefficient (v);
+		}
+	}
 	return model_to_view_coord_y (v);
 }
 
diff --git a/gtk2_ardour/automation_line.h b/gtk2_ardour/automation_line.h
index 9fa64552e4d..5d2f113ace6 100644
--- a/gtk2_ardour/automation_line.h
+++ b/gtk2_ardour/automation_line.h
@@ -128,7 +128,7 @@ class AutomationLine : public sigc::trackable, public PBD::StatefulDestructible
 	std::string get_verbose_cursor_relative_string (double, double) const;
 	std::string fraction_to_string (double) const;
 	std::string delta_to_string (double) const;
-	double string_to_fraction (std::string const &) const;
+	double string_to_fraction (std::string const &, double old_fraction) const;
 
 	void   view_to_model_coord_y (double &) const;
 
diff --git a/gtk2_ardour/control_point_dialog.cc b/gtk2_ardour/control_point_dialog.cc
index 6f111d45b2f..ac7622332a1 100644
--- a/gtk2_ardour/control_point_dialog.cc
+++ b/gtk2_ardour/control_point_dialog.cc
@@ -73,7 +73,9 @@ ControlPointDialog::ControlPointDialog (ControlPoint* p)
 }
 
 double
-ControlPointDialog::get_y_fraction () const
+ControlPointDialog::get_y_fraction (ControlPoint* p) const
 {
-	return point_->line().string_to_fraction (value_.get_text ());
+	double const old_fraction = 1.0 - (p->get_y () / p->line().height ());
+
+	return point_->line().string_to_fraction (value_.get_text (), old_fraction);
 }
diff --git a/gtk2_ardour/control_point_dialog.h b/gtk2_ardour/control_point_dialog.h
index 539a41c8b3f..54a13d5e8fa 100644
--- a/gtk2_ardour/control_point_dialog.h
+++ b/gtk2_ardour/control_point_dialog.h
@@ -27,7 +27,7 @@ class ControlPointDialog : public ArdourDialog
 public:
 	ControlPointDialog (ControlPoint *);
 
-	double get_y_fraction () const;
+	double get_y_fraction (ControlPoint *) const;
 
 private:
 	ControlPoint* point_;
diff --git a/gtk2_ardour/editor_mouse.cc b/gtk2_ardour/editor_mouse.cc
index 85746d4b74c..1dd525c14ee 100644
--- a/gtk2_ardour/editor_mouse.cc
+++ b/gtk2_ardour/editor_mouse.cc
@@ -2376,7 +2376,7 @@ Editor::edit_control_point (ArdourCanvas::Item* item)
 	}
 
 	for (ControlPoint* const & control_point : selection->points) {
-		control_point->line().modify_point_y (*control_point, d.get_y_fraction ());
+		control_point->line().modify_point_y (*control_point, d.get_y_fraction (control_point));
 	}
 }